The Movement of Charged Particles in a Magnetic Field. By Emily Nash And Harrison Gray. Preview. Magnetic fields and how they are created Magnetic field of the earth Solar wind and how the earth’s magnetic field affects it
The Movement ofCharged Particlesin aMagnetic Field
Magnetic Fields are created by moving
charged particles, and only affect moving
Forces between two electric currents is what causes a magnetic force. Two parallel currents flowing in the same direction attract each other, while two parallel currents flowing in opposite directions repel each other.
When there exists a steady
stream of electrons, a negatively charged particle, an electric
current forms, which produces
a magnetic field.
This force leads to the idea of the north and south poles of a magnetic field.
Creating a Magnetic Field
It is possible to create a magnetic field by producing an electric current, or vice versa.
When current passes through a coil of wire, it
generates a magnetic field along the access of the coil.
This is called electromagnetism
Earth's Magnetic Field
The Earth itself is a magnet, with a magnetic north
pole and south pole.
The origin of the Earth’s magnetic field is said to be a result of the dynamo effect, electric currents produced by the rotation of the iron-nickel core.
The Earth’s magnetic field continually traps moving charged particles coming from the sun, called solar wind.
High concentrations of these particles within the field are called the Van Allen Radiation belts.
Solar Wind consists of gases comprised of protons, electrons, and ions which hurl towards the earth from the sun at velocities of 450 km/sec or higher.
The path of these particles change almost directly as they hit the earth’s magnetosphere at the region called the bow shock.
The impact of the solar wind causes
The field lines facing the sun to compress,
While the field lines on the other side stream back to form a
Because the charged particles of the rays are deflected around the magnetosheath,
the earth is protected from most of the deadly radiation.
Solar Wind Cntd
Some solar wind particles, however, do escape the earth’s magnetosphere and
contribute to the Van Allen radiation belts.
In order to better understand the motion of particles through a magnetic field,
we have conducted an experiment involving creating an electron beam and running it through magnets as a parallel to solar wind entering the earth’s magnetic field.
Cathode Ray Tube Cntd.
Since change in energy is the voltage times the charge
Therefore v= √(2qV/m)
The potential energy
of electrons is converted
to kinetic energy
Electrons are attracted to positively charged
plate. They accelerate towards it and small
percentage escape the plate through small
hole, creating electron beam.
Plate is heated and
electrons boil off.
Potential Energy= ½ mv^2
Cathode Ray Tube
Calculating the Velocity of the Electrons
We now know that v= √(2qV/m), so we can now easily find the
velocity of our beam of electrons.
q(charge) of an electron= -1.6•10^-19
m(mass) of an electron=9.11•10^-31 kg
In order to predict
the angle at which
the electrons are
deflected, we must
the force that the
magnetic field inserts
upon the beam
To do this, we use the equation:
Like Solar Wind,
the electrons in the
CRT beam are deflected
when entering a
therefore the electron
The force is always
Perpendicular to the magnetic field
And the velocity of the electrons
Calculating the Strength of the Magnetic Field
In order to find the force of the magnetic field, we must first calculate its strenghth.
Since F=qvB and, according to Newton’s second law, F=m•v²/r, we can deduce that
mass= 9.11•10^-31 kg
velocity= 6.492•10^6 m/s
Charge= 1.6•10^-19 C
And we measured the distance of the electron beam from the magnets
to be .075 meters
Therefore B= (9.11•10^-31)(6.492•10^6)/(1.6•10^-19)(.075)
Calculating the Force of the Magnetic Field
Now that we know the strength of the magnetic field at the electron beam, we can
Calculate the force which the field exerts upon the electrons.